1. Field of the Invention
The present invention relates generally to imaging systems and methods. More particularly, the present invention relates to high definition imaging systems and methods.
2. Description of the Prior Art and Related Background Information
Electronic image sensors such as charge-coupled devices (CCDs) are well known. In a CCD imager, image information associated with each pixel in a pixel array is accumulated as electrical charge which is read out of the imager as image data. As a result CCDs, and other electronic imaging devices, require a series of precise timing pulses to sequentially read the image data from the image sensor. These precise timing pulses are provided to the electronic image sensor at a particular clock frequency. This read out clock rate will determine the amount of image data (number of pixels) which can be read out of the imager per unit time. This clock rate therefore limits the image resolution for a given frame rate.
High resolution, high frame rate imaging systems are becoming important for a number of applications such as HDTV cameras, medical imaging and other applications where high quality images are needed. For such high frame rate and high definition imaging, very high read out clock rates are needed. Indeed, the clock frequencies which are needed to transfer the charge from all the pixels of the imager within the allowed time tend to be near or above the limits of the speed at which charge can be effectively transferred within conventional CCD imager designs. Similar constraints exist for other electronic imagers such as CMOS image sensors. Also, when fabricating image sensors with high resolution, manufacturers are particularly cautious to prevent noise and distortion that may result during read out. As a result, high resolution high frame rate electronic imagers typically require special designs which can be very expensive relative to imagers adapted to run at lower clock rates. As a specific example, a typical high-definition (HD) CCD sensor, such as the Sony ICX204AL, which is adapted for machine vision applications and is rated for only 15 frames per second in standard progressive read-out mode is a fraction of the cost of a high-definition (HD) CCD sensor that can run at a clock rate adapted for standard frame rates (50 or 60 frames per second).
Therefore, a need exists for a low cost imager capable of providing high definition images at high frame rates.